Control system



July 12, 1949. A. D. TRENOR 2,475,863

CONTROL SYSTEM Filed 001;. 4, 1946 2 Shecs-Sheet 1 TlMlNG DEVICE INVENTOR B 0| L ER ALBERT o. TRENOR.

23 ORNEY Patented July 12, 1949 UNITED STATES PATENT OFFICE CONTROL SYSTEM Albert D. Trenor, Gloucester, Mass., assignor to John Hays Hammond, Jr., Gloucester, Mass.

Application October 4, 1946, Serial No. 701,158

1 Claim.

This invention relates to condition control systems and more particularly to an improved system for automatically maintaining the temperature of a room at a predetermined level.

The invention further provides means for varying the amount of heat or cooling supplied to a room in proportion to the variations of the temperature of the room from a predetermined standard.

The invention also consists in certain new and original features of contruction and combinations of parts hereinafter set forth and claimed.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of its organization may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which Fig. 1 illustrates diagrammatically the invention as applied to a hot water heating system, and

Fig. 2 is a modified form of the invention as applied to a warm and cold air Ventilating and air conditioning system.

Like reference characters denote the parts in the several figures of the drawing.

In the following description parts will be identified by specific names for convenience, but they intended to be as generic in their application to similar parts as the art will permit.

Referring to the embodiment of the invention shown in Fig. 1, an oil fired hot water boiler ll, of standard and well known construction preferably is provided with aquastatic control adapted to maintain the Water in the boiler H at a uniform temperature. The boiler ii is connected by feed pipe I2, to a control valve l5, which in turn is connected to a radiator 18. The radiator I8, is connected by a return pipe 22, and return line 2-3 to a circulator 25 which in turn is connected to the boiler ll. Feed pipe l3 leads to other radiators which are individually controlled in the same manner as radiator IS. A single control unit is shown herein for purposes of illustration. It is to be understood that this unit is repeated for each radiator.

The valve !5 is operated by a control mechanism 28 which in turn is controlled by a thermostat Bl. Power for operating the control mechanism 2B is supplied from a source 34 such for example as a 110 volt A. C. line. The power source 34 is connected thru a step-down trans- 2 former 35 to a timing device 36, of any well known and standard construction, which is adapted to supply low voltage power to output terminals 31 and 38 at predetermined selected time intervals and for a predetermined length of time, i. e. for 30 seconds every 10 minutes.

The control mechanism 26 comprises a valve shaft M which controls the opening and closing of the valve I5. Secured to the valve shaft M is a worm Wheel 42 which meshes with a worm is mounted on the shaft of a reversible motor 44, the rotation of which is controlled by a suitable reversing mechanism 45.

One side of the reversing mechanism 45 is connected by a lead at to a movable contact arm ll. The other side of the reversing mechanism 45 is connected by a lead l!) to a movable contact arm 5|.

Secured to the shaft 4| is an arm of insulating material 53 which at suitable times engages the movable contact arms i! and 55. Also secured to the shaft ll is one disc of a magnetic clutch 54 the other disc of which is mounted on a shaft 55 which is coaxial with the shaft M. The magnetic clutch. is controlled by a coil 56 which is connected by leads 5'? and 58 to the output terminals 31 and 38 of the timing device 36. The lead 58 is connected by a lead 59 to the common return line of the reversing mechanism 45.

Secured to the shaft 55 is a disc Bl of insulating material on which is mounted a pin 62 to which are secured the ends of tension springs 63 and 64 the other ends of which are fastened to anchor pins 65 and 66 respectively. The springs 53 and 64 tend to maintain the disc ill in a central position when the magnetic clutch M is disengaged.

Mounted on the disc iii are two conducting segments 6'! and 68. The segment at is normally engaged by four brushes l ll l and the segment 6&3 is normally engaged by four brushes iii-1B. The brushes ll and F8 are connected by leads 8! and 82 respectively to fixed contacts and 84 which normally engage the movable contact arms 41 and ill respectively.

The thermostat 3! comprises a base 35 on which is rotatably mounted a disc 86 which carries a dial segment 81 on which is engraved a temperature scale 88 which in turn registers with a reference mark 89. Mounted on the disc 86 is a thermostatic element 9! of standard bi-metallic construction. Mounted on but insulated from the thermostatic element 9| is a contact 92 which is connected by a flexible lead 93 to the lead 5].

Normally the contact 92 rests on a segment of insulation 94. On each side of the insulation 94 are three conducting segments 95-9| and IM- I03. The three segments 959| are connected to the three brushes '|2'l4 respectively and the three segments "ll-I03 are connected to the three brushes |5|'| respectively.

Operation of Fig. 1

The mechanism is shown in Fig. 1 as in full operation with hot water from the boiler I I being circulated thru the radiator l8 by the circulator 25. The control valve I5 is assumed to .be open the proper amount to allow sufiicient hot water to pass thru the radiator H! to maintain the temperature of the room in which the radiator is mounted at 70 F. At the end of every ten minutes the timing device 36 will cause the circuit 5|--58 to be energized. This will cause the magnetic clutch 54 to be engaged due to the energization of the coil 56. If the contact 92 is on the insulation 94 as shown the motor 44 will not be energized and the valve |*5 will remain unchanged.

If, during the next interval of the timer, the temperature of the room in which the radiator I8 is mounted should drop to say 69 F. the bimetallic element 9| will be flexed to cause the contact 92 to engage the segment 91. When the timing device 36 again energizes the circuit 5| 58 the clutch 54 will be engaged and a circuit will be closed from the contact 92, segment 91, brush T4, segment 61, brush "H, lead -8|, contact 83, movable contact 41 and lead 46 to the reversing mechanism 45 which will cause the motor 44 to drive the worm wheel '42, by means of the worm 43, in a counter clockwise direction as seen from above. This motion will be transmitted by the shaft 4| through the clutch 54 to the disc 6| and will continue until the brush '14 engages the insulation between the segments 61 and 68 at which time the circuit through the motor 44 will be broken. The valveshaft 4| will then come to rest after having been rotated a predetermined amount toward open position.

When the timing device 36 opens the circuit 51-58 after holding it closed for '30 seconds, for example, the clutch '54 will open and release the disc 6| which will then be returned to its midposition by the centering action of the springs 63-64.

The valve l5 will now have a slightly greater opening and will allow more hot water to pass thru-theradiator |'8. If this is sufficient to cause the temperature of the room to be increased to 70 F. the contact 92 will be restored to the insulation 94. If, however, the temperature remains low at the next actuation of the timer the same operation will be repeated to open the valve |'5 a further amount.

If the temperature in the room should drop to say 63 F. the contact 92 will engage the segment 96 and when the timingdevice 36 again energizes the circuit 5'|58 a circuit will be closed thru the contact 1-3 to cause the motor 44 to drive the shaft 4| and disc 6| in a counterclockwise direction until the brush 13 has moved onto the insulation. This will rotate the valve shaft 4| a greater amount than if the room temperature were 69 F. and further open the valve I5 to supply more hot water to the radiator I8. When the circuit -5'|--58 is again opened by the timer the disc 6| will be again centered.

If the temperature of the "room drops to say 67 the circuit will be-closed through the brush 12 and the valve 1 5 will be iurther opened.

If the temperature of the room increases above 70 F. the contact 92 will progressively engage the various segments l0 63, which will close a circuit through the other side of the reversing mechanism to cause the motor 44 to rotate the valve stem 4| in a closing direction by difierent amounts dependent on the increase of temperature. This will close the valve I5 progressively at the timed intervals until the temperature drops to The thermostatic element 91 may be set to maintain any desired room temperature as indicated by the scale 88.

If the valve stem 4| is rotated in a counterclockwise direction until the valve |5 is fully open the arm 53 will engage the movable arm 41 and break the contact 83, thus opening the circuit through one side of the reversing mechanism 45 so as to prevent a further drive of the valve shaft 41. In a like manner the arm 5| acts as a limit switch when the valve I5 is fully closed.

This system provides means at predetermined time intervals for checking the temperature of each room and if this temperature is not that called for by the setting of the room thermo sta-t the valve controlling the amount of heat supplied to the radiator of each room will be so adjusted that the temperature of each room will be quickly brought back to normal.

It is seen from the foregoing description that a system is provided which supplies continuously a controlled amount of heat to each room according to the heat requirements of the room as distinguished from the on and off type of control which frequently results in wide temperature fluctuations.

While a heating system is depicted in Fig. 1 the invention may also be applied to a cooling system in which case the boiler may be replaced by a cooler containing brine or other suitable fluid, which is maintained at any desired low temperature by any well known type of cooling device. In this case the connections to the reversing mechanism would be reversed so that if the temperature of the room increased the valve 15 would have to be opened wider to permit more cooling fluid to pass through the radiator l8.

Referring to the embodiment of the invention shown in Fig. 2 a standard type of ventilating and air conditioning system is shown diagrammatically. This system in general comprises a warm .air system )5 and .a cool air system I06. The warm air system Hi5 consists of a hot air furnace H17 surrounded .by a jacket I08. At the top of the jacket 168 is a duct I09 leading to :a. humidifier which in turn is connected to the warm air supply duct |2.

The cool air system 06 consists .of a cooling unit H3 of well known andstandard construction surrounded by a jacket '|.'|4. This jacket communicates with a duct H5 which in turn is connected to a. dehumidi'fying device M6 for removing excess moisture from the cool air. The dehumidifier |f|6 is connected to the cool air supply duct 1 H.

The warm and cool air systems may be supplied either with fresh air from outdoors through a duct H8 or with recirculated air from indoors through a duct H9 which is connected to openings in the floors of the various rooms to be air conditioned. A damper |2| is provided for mixing the fresh and recirculated air in any desired proportion. Blowers I22 and |23 are located in the warm and cool air supply ducts I24 and I for the purpose of continuously :cir

culating the warm and cool air thru the system.

The warm and cool air supply ducts H2 and II! are connected to a mixing chamber I2'l which is provided with a hinged damper I29. This damper is connected to one end of a link I29 the other end of which is pivoted to a gear segment I3I mounted for rotation about the point I32. Meshing with the gear segment I3I is a bevel pinion I39 which is secured to the shaft 4! of the control mechanism 26. This mechanism is connected to the thermostat 3| and to the supply leads 5! and 58 in a similar manner to that described in connection with Fig. 1. The mixing chamber I21 is connected by a duct I34 to an opening I35 near the ceiling of the room I35 which is to be air-conditioned.

Operation of Fig. 2

In the operation of the modified form of the invention shown in Fig. 2 the ducts H2 and II! are kept continuously supplied with warm and cool air respectively at uniform temperatures and relative humidities in a manner well known in the art. As shown in Fig, 2 the mechanism is in full operation with both warm and cool air being combined in the mixing chamber I2! and passing through the duct I34 and opening I35 into the room I36. The damper I28 is assumed to be open the proper amount to allow sufficient warm and cool air to pass into the room I39 to maintain the temperature of this room at 70 F. At the end of every ten minutes the control mechanism 26 will be activated as described in connection with Fig. 1 to rotate the shaft M in one direction or another depending on whether more or less heat is to be supplied to the room I36. If, for example, the thermostat 3| is calling for more heat the shaft M will be rotated so as to cause the gear segment I3I to be rotated in a counter-clockwise direction as seen in Fig. 2. This will cause the link I29 to move to the right which in turn will move the damper I28 to the right thus permitting more warm air and less cool air to enter the room I35 which will cause an increase of temperature in the room. If the room I36 is too warm the shaft 4| will be rotated in the opposite direction to cause the gear segment I3I to be rotated in a clockwise direction which by means of the link I29 will move the damper I28 to the left to decrease the supply of warm air and increase the supply of cold air.

The link mechanism I29 et cetera is so designed and proportioned that the motion of the damper I28 is less at the two extremes of its motion than in the middle. That is, when the damper was closed on the hot air side the opening of this damper will be more gradual than it will be when it is in the middle of its motion, and the same way when it is over to the right so as to close off the cold air duct.

Although only a few of the various forms in which this invention may be embodied have been shown herein, it is to be understood that the in vention is not limited to any specific construction but may be embodied in various forms without departing from the spirit of the invention as defined by the appended claim.

What is claimed is:

A temperature control system comprising a source of temperature control fluid a variable valve connected, to control the flow of said fluid, a thermostat responsive to the temperature to be controlled and having contacts arranged to be progressively closed in response to variations of said thermostat from a set value, a reversible motor connected to vary the opening of said valve, a controller having conducting segments and a central insulating segment, brushes connected to said contacts and engaging said conducting segments at various distances from said insulating segment, centering means for said controller, a clutch to drive said controller with said valve, connections including said brushes and contacts to drive said motor in a direction and by an amount dependent upon the selective closing of said contacts, and timed means to render said motor connections operative and simultaneously to engage said clutch intermittently for predetermined periods, whereby said valve opening is altered in accordance with the temperature vari ations between said periods.

ALBERT D. TRENOR.

REFERENCES CITED The following referenrces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,569,994 Martin Jan. 19, 1926 1,690,829 Mozzocco Nov. 6, 1928 1,985,539 Hartwig Dec. 25, 1934 1,987,311 Poole Jan. 8, 1935 1,997,412 Fischel Apr. 9, 1935 2,005,586 Koci June 18, 1935 2,218,454 Midyette Oct. 15, 1940 

